Exhaust manifold



SePt- 23, 1958 w. s. woLFRAM 2,852,910

' EXHAUST MANIFOLD Filed Dec. 29, 1953 INVENTOR ATTORNEY United States Patent O EXHAUST MANIFOLD William S. Wolfram, Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 29, 1953, Serial No.`400,885

1 Claim. (Cl. 611-29) The present invention relates to internal combustion engines and more particularly to the exhaust manifolds for such engines.'

It is desirable that the exhaust manifold for an internal combustion engine be designed to produce the minimum amount of back pressure when the exhaust gases are discharged from the engine into the manifold. Tjhis not only reduces burning of the exhaust Valves by decreasing their operating temperatures but it also reduces the Iamount of dilution of the incoming combustible charge by permitting a more complete exhausting of the burned gases from the cylinder during the exhaust stroke. Although there are numerous exhaust manifolds employing various forms of streamlined passages to decrease the resistance to the flow of exhaust gases therethrough, they all have bends or turns in them that deflect the ow of the exhaust gases. It is a well accepted principle of Huid mechanics that when a fluid 'flows around a turn in a conduit that the difference between the velocity of the uid mass turning on the `shorter radius and the velocity of the fluid mass turning on the larger radius will tend to cause `the two uid masses to reverse their relative radial positions. This produces a turbulent flow havingr two counter-rotating fluid columns and this in turn materially increases the resistance to the fluid ow.

Since it is desirable to dellect the ow of exhaust gases i around a turn at least at the region where they are discharged from` the manifold into the exhaust pipe, it is proposed to artificially induce a spiral ilow of gases in 4this region so that there will be but a single rotating column of exhaust gases. Such a flow condition will tend to decrease the back pressure because there will be less wasted energy than when there are two counter-rotating columns.

In addition since there will be a spiral ow present in the above-mentioned region, it is proposed to position the passages in the exhaust manifold so that the rotation of the gases will always remain in the same direction regardless of which cylinder is discharging gases into the manifold. This will further reduce the back pressure by eliminating the expenditure of energy required to start and stop a rotating column every time its direction of rotation is reversed.

In the drawings:

Fig. 1 is a fragmentary view of a portion of 'an engine showing an exhaust manifold embodying the present invention.

Fig. 2 is a cross sectional view of the manifold employed in Fig. 1.

Fig. 3 is a schematic representation of this manifold and has arrows positioned to diagrammatically represent the flow of exhaust gases therein.

Referring to the drawings in more detail, the present invention may be embodied in any suitable exhaust mani* fold 10. Although the manifold may be adapted for installation on any type of engine 12, in the present instance itis employed on an inline engine 12. This engine 12 may have six cylinders which discharge the exhaust Patented Sept. 23, 1958 gases through two sets of Siamese exhaust ports 14 ICC and 16 in the center of the engine 12 and single exhaust ports 18 and 20 on each end.

The manifold 10 is an elongated member which forms a hollow housing 22 adapted to be secured to the side of the engine 12 by bolts 24 or any other suitable means. The housing 22 may be provided with a plurality of inlets 26, 28, 30 and 32 that are positioned to register with the exhaust ports 14, 16, 18 and 20 when the manifold 10 is secured to the engine 12. Thus when the engine 12 is is in operation these inlets 26, 28, 30, and 32 will direct the ow of gases from the exhaust ports 14, 16, 18 and 20 into the manifold 10 so that they may be collected for discharge into an exhaust system 34. Although this system 34 may have but a single exhaust pipe, it has been found that by employing two independent exhaust pipes 36 and 38 the flow resistance will be lowered enough to materially decrease the back pressure. Each of the exhaust pipes 36 and 38 may be provided with an enlarged end 40 and 42 which may be secured to flanges 44 and 46 on the bottom of the manifold 10. The manifold 10 may be provided with outlet passages 48 and 50 which extend through the flanges 44 and 46 so as: to form apertures in the center of the flanges 44 and 46. Thus when the exhaust pipes 36 and 38 are secured to the llanges 44 and 46, the exhaust gases collected by the inlets 26, 28, 30 and 32 will be discharged fromthe outlet passages 48 and 50 into the exhaust pipes 36 and 38.

The manifold may have a chamber formed in the center thereof for collecting theexhaust gases and directing them into the outlet passages 48 and 50. The manifold 10 may have a separate chamber 56 and 58 for each of the outlet passages 48 and 50. However, it should be understood any number of chambers may be employed. Since the chambers 56 and 58 are not interconnected in the present embodiment, the manifold 10 may be divided into a front and a rear portion 60 and 62, each of which contains one chamber 56 o1' 58 that communicates with one of the exhaust conduits 36 or 38 by means of the exhaust passages 48 or 50.

The front portion 60 of the manifold 10 has a pair of inlets 26 and 28 that register with the front engine exhaust port and the Siamese port 14 adjacent thereto. Each of these inlets 26 and 28 forms the end of a short passage 64 and 66 which communicates with a duct 68 that extends longitudinally of the manifold 10 in a substantially horizontal direction. Thus the exhaust gases from the ports 14 and 18 will ow through the passages 64 and 66 into the duct 68. The rear end of the duct 68 communicates with the front chamber 56. The duct 68 is spirally disposed about this chamber 56 so as to intersect the chamber in a substantially tangential relation. It is thus apparent that as the exhaust gases tow from the duct 68 into the chamber 56 they will enter on a tangent and cause a cyclonic or spiral ilow of gases in the chamber 56. The gases will then ow downwardly into the exhaust conduit 36 with a spiral pattern that may gradually be dissipated as the exhaust gases continue their travel in the conduit 36. To assist in diverting the flow around the right angle into the exhaust conduit 36, it may be desirable to have the end of the duct 68 inclined slightly downwardly. It will thus be `apparent that the gases may negotiate a substantially right angle turn without creating excessive turbulence. It should be noted that since the gases from either port 14 or 18 always enter the chamber 56 in the same tangential relation, the flow of gases in the chamber 56 will always rotate in the same direction. Thus it will be seen that once a spiral ow is started, it will continue and that the exhaust gases from one cylinder will not tend to oppose the rotation created by another cylinder. This will prevent wasting the energy required to start and stop a rotating column of gas every time the 3 direction ofrotation is reversed and thus materially reducing the ow resistance.

The rear portion 62 of the manifold 10 is very similar to the front. section 60 however, the duct means comprises two ducts 70 and 72 thaty communicate directly with the rear port 20 and thesiamese port 16 adjacent thereto. The ducts 70 and 72 are spirally disposed about the chamber 58 so as to intersect the chamber 58 on diametrically Vopposite vsides in substantially the same direction and tangential relation. Thus as explained above as the gases travel from the ducts 70 and 72 into the chamber S8 a spiral flow will be created which will reduce the ilow resistance. By positioning the ducts 70 and 72 so as to intersect the chamber S8 in the same direction any spiral flow of gases will always be in the same direction. Thus the. direction of rotation is independent of the cylinder which is exhausting. It may be noted that the rotation in one chamber may be opposite to that in the other chamber as long as the rotation of the gases in any one chamber remains unidirectional. Since the chambers inthe present instance are not interconnected with each other, the counter-rotation will not cause any interference.

If it is desired to provide an exhaust heating of an intake manifold suchV as contained in application S. N. 331,371-Stolte led January 15, 1953, now Patent No. 2,761,437, one of the chambers may form a heat box for diverting hot exhaust gases into the intake manifold. In the present instance the front chamber 56 is provided with a butterly valve 74. During normal engine operating conditions the engine 12 will be hot and the valve will be disposed in an inclined position that will tend to detiect the gases downwardlyv into the exhaust passage 48 without in any way interfering with the spiral rotation thereof. However when the engine 12 is cold and it is desirable to heat the intake manifold, a suitable thermostatic element (not shown) may move the buttery valve into a substantially vertical position as shown by the dotted lines in Fig. 2. When the valve is in this position, it will divide the chamber 56 into two parts. Thus when the exhaust gases enter the chamber 56 the valve 74 will force them to low vertically up through the opening 76 into the intake manifold (not shown). After passing through the intake manifold they will be returned to the second half of the chamber 56 and then into the exhaust conduit 36. Although the valve 74 in this position will prevent the gases flowing in a spiral pattern, it should be noted that this is only a temporary condition and as soon as the engine reached eticient operating temperatures, the valve 74 will be moved to its original position and thus allow the desired rotational flow of the gases to take place.

It is to be understood that, although the invention has been described with specic reference to a particular embodiment thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claim.

What is claimed is:

An exhaust manifold for collecting a flow of exhaust gases from a plurality of exhaust ports on an engine and discharging Said flow into an exhaust conduit, said manifold. comprising a housing having longitudinally extending duct means therein, a plurality of inlet openings positioned in said housing to register with said exhaust ports for directing said flow of exhaust gases into said housing at' longitudinally spaced points, and an outlet passage in said housing communicating with said duct means between said inlets for discharging said flow of exhaust gases into said exhaust conduit, the portions of said duct means on the opposite sides of said outlet passage being positioned to discharge said ow of exhaust gases spirally into said passage at susbtantially diametrically opposite sides and in the'same tangetial direction for creating a uni-directional Cyclonic oW' in said exhaust conduit.

References Cited in the le of this patent UNITED STATES PATENTS 1,250,950 Bolton Dec. 25, 1917 1,522,032 Scarf Jan. 6, 192,5 1,760,682 Boysen May 27, 1930 1,838,834 Holzer Dec. 29, 1931 1,886,383 Edwards Nov. 8, 1932 2,034,119 Shebat Mar. 17, 1936 2,356,782 Muller Aug. 29, 1944 FOREIGN PATENTS 622,824 France Mar. 7, 1927 794,512 France Dec. 12, 1935 398,857 Great Britain Sept. 22, 1933 461,757 Great Britain Feb. 24, 1937 

